The present invention relates to an automatic motor vehicle body assembly and welding station with innovative characteristics which allow fast and accurate verification of the good performance of the assembly and welding operations without the need of conveying the body out of the station.
In the prior art, automatic assembly and welding stations made up of facing conformator pairs, i.e. movable supporting frames for the body holding and welding equipment, are well known. Between the conformators runs a conveyance way for the bodies to be subjected to the various processing steps. When a body arrives in the station the conformators move toward each other to approach the body from opposite sides and the equipment is taken into position to work on the body. After performance of the planned operations the conformators withdraw and the body is freed to be conveyed from the runway to the next processing station.
Over time variants of the structure of the stations of this type have been proposed mainly to make movement of the conformators more efficient and/or more satisfactory for specific requirements. For example, stations with conformators turning around an upper or lower horizontal axis, stations with conformators translating parallel to themselves in a direction transversal to the runway, or even stations with conformators replaceable automatically with others taken from appropriate automatic storerooms to allow fast adaptation of the station to processing of a different body model have been proposed. The basic principle of the stations proposed heretofore has however always been the same.
In body production it is clearly important to respect very precise dimensional characteristics. In the prior art, to control assemblies performed by the above mentioned stations it is usual (commonly by sampling) to take an assembled body, set it on a measurement bench (usually automatic) and verify whether the measurements taken this way are within the preset tolerances. If the measurement gives a negative outcome the system is stopped and investigation takes place to find the part thereof responsible for the error, which is usually caused by lack of setting, wear or failure of some holding member in a welding station.
Clearly, even though widely followed, such a procedure is quite costly because, among other reasons, of the long stoppage of the installation it causes. The cost caused by the fact that the body is not acceptable but is uselessly subjected to further processing after that which produced the fault should be taken into consideration. To this must be added the fact that if the inspection is performed by sampling the fault is observed statistically after a certain number of faulty bodies have already been produced.
The general purpose of the present invention is to remedy the above mentioned shortcomings by making available an assembly station of the type with conformators allowing real-time identification of assembly faults and dimensional parameters of the product out of tolerance.
In view of this purpose it was sought to provide in accordance with the present invention a motor vehicle body assembly and welding station comprising a pair of facing tool support conformators designed to work on the body which is taken between them by a conveyor system with the conformators being movable between a rest position in which the body is free to enter and exit the station and a work position in which the tools are near the body to work on it characterized in that at least some of the tools comprise measurement means for the relative position of facing body parts and that the conformators have an intermediate position between said work and rest positions with control means taking the conformator into said intermediate position and activating the measurement means to detect the agreement of body dimensional parameters with predetermined measurement intervals and issue acceptance or rejection signals for the body on the basis of the survey result.